Question on Backflow
What is Backflow?
Definition of Backflow:
Water normally flows in one direction from the public water system through the customer’s cold or hot water plumbing. If the water begins to flow in the opposite direction (away from the intended user back towards the City supply), due to back pressure or back siphonage, it can become contaminated from cross connections. Backflow can occur in any commercial, industrial or residential property.
Types of Backflow – Back Siphonage
Backflow from back siphonage is caused by a negative or sub-atmospheric pressure; a drop in the water main pressure. Events that can cause back siphonage include a water main break or a high rate of water withdrawal, such as fire fighting. Back siphonage is the flowing back of used, contaminated, or polluted water from a plumbing fixture, irrigation system or vessel into a potable water supply (drinking water supply) due to a negative pressure in the supply piping.
Types of Backflow – Back Pressure
Backflow from back pressure is caused when the water system is connected to a system or supply operating at a higher pressure than the municipal water system. A booster pump or elevated piping are examples of connections that operate at a higher pressure that cause back pressure.